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The S-parameter retrieval has proved to be an efficient approach to obtain electromagnetic parameters of metamaterials from reflection and transmission coefficients, where a slab of metamaterial with finite thickness is regarded as a homogeneous medium slab with the same thickness [D. R. Smith and S. Schultz, Phys. Rev. B 65, 195104 (2002)]. However, metamaterial structures composed of subwavelength unit cells are different from homogeneous materials, and the conventional retrieval method is, under certain circumstances, not accurate enough. In this paper, we propose an advanced parameter retrieval method for metamaterial slabs using an inhomogeneous model. Due to the coupling effects of unit cells in a metamaterial slab, the roles of edge and inner cells in the slab are different. Hence, the corresponding equivalent medium parameters are different, which results in the inhomogeneous property of the metamaterial slab. We propose the retrievals of medium parameters for edge and inner cells from S parameters by considering two- and three-cell metamaterial slabs, respectively. Then we set up an inhomogeneous three-layer model for arbitrary metamaterial slabs, which is much more accurate than the conventional homogeneous model. Numerical simulations verify the above conclusions. [ABSTRACT FROM AUTHOR]

In this paper, a Ka-band wideband filter with a reconfigurable mode of bandpass-bandstop switching is presented. As a low-Q resonator, a rectangle ring with a straight "tail" is inserted into the central E-plane of a waveguide to realize the wideband performance. With the "ON" or "OFF" state of the PIN diode, the EM field driving by the resonator may be the same direction with or suppress the TE10 of the waveguide, which makes the filter be reconfigurable. At the frequency of 33GHz-37GHz, the insertion loss is lower than 1 dB at band-pass mode, and when it is working as a band-stop filter, the insertion loss is more than 15 dB on the whole frequency band. [ABSTRACT FROM AUTHOR]

This paper presents a reconfigurable WIFI band filter with three switchable modes. Half wavelength resonators coupled with a microstirp transmission line are used to design the frequency of WIFI band. PIN switches mounted at the microstrp near the resonators are used to switch the working modes of the WIFI filter. This WIFI filter is able to work at both 2.45GHz and 5.8GHz with the resonators working at different modes. A dual-band band-stop mode is also available with the filter. A centrally loaded resonator technology is used to suppress the harmonic of 2.45GHz witch would interfere the performance at 5.8GHz. The isolation is enhanced by more than 40 dB with the structure in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a new substrate integrated waveguide (SIW), which is called reconfigurable substrate integrated waveguide (RCSIW) is proposed. RCSIW is derived from SIW and tunable technology which is widely used in microwave system. It is realized by replacing the side-wall metal posts of SIW with several grounded varactors which are employed to make the SIW tunable. The cutoff frequency and propagation constant can be reconfigurable by controlling these varactors. A RCSIW is designed to test these properties with the input and output of microstrip line. Ansoft HFSS was used to get the characteristics of RCSIW. The results show the reconfiguration of RCSIW. [ABSTRACT FROM AUTHOR]

In this paper, a quasi-hexagon shaped band-stop frequency selective surface with a wideband RCS reduction is proposed. In terms of structural mode scattering, we design a kind of band-stop FSS as a substitute for the traditional metal reflection board grounded on a hexagon FSS prototype and the typical Koch fractal curve. Patch dipole antenna is used to confirm the validity of this method and the result of simulation shows that relative RCS of the patch antenna with metal ground, there is a considerable out-of-band RCS of the antenna with band-stop FSS ground plane about 11.3dB reduction on average, and 27.3dB reduction on 5.8 GHz. [ABSTRACT FROM AUTHOR]

We create an invisible gateway simply by putting electric and magnetic superscatterers in a metallic waveguide. The characteristics of the electric and magnetic resonators are analyzed in a metallic hollow waveguide, and the dual-mode superscattering property is discussed in detail to broaden the bandwidth of the invisible gateway. Good agreement is achieved between the simulation and measurement for such an invisible gateway. The present work help readers understand easily how an invisible gateway works (or makes sense) in a classical way without using any complex metamaterial or complicated method of transformation optics. [ABSTRACT FROM AUTHOR]

A modulatable electromagnetically induced transparency (EIT) is achieved using a slotted circle ring structure. The circle ring structure is used to induce a polarisation-independence resonance with a low Q factor, while the slot is etched to obtain a polarisation-dependence resonance with a high Q factor. The EIT effect is obtained when the two resonances have nearby resonant frequencies but with different Q factors. As both resonant modes are excited by the external field independently, different coupling strength is achieved simply by adjusting the polarisation angle. Then the transmission of EIT is successfully modulated. The design concept is well validated both by simulation and measurement. [ABSTRACT FROM AUTHOR]